#include<queue>
#include<cmath>
#include<cstdio>
#include<cstdlib>
#include<iomanip>
#include<iostream>
#include<algorithm>
using namespace std;
priority_queue<double>pq;
signed main(void) {
	ios::sync_with_stdio(false);
	int n; cin >> n;
	for (int i = 0, w; i < n; i++)
		cin>>w, pq.push((double)w);
	while (pq.size() > 1) {
		double top1 = pq.top(); pq.pop();
		double top2 = pq.top(); pq.pop();
		pq.push(2 * sqrt(top1*top2));
	}
	cout << fixed << setprecision(3) << pq.top() << endl;
}